The title of this thread makes me laugh.
If fanbases determined anything, Firefly and Farscape would still be on the air, the Star Wars prequels wouldn't have sucked mighty, mighty balls, and ME3 would have had a remade "Priority Earth", "full romance" and "happy ending" DLC by now.
Conversely, fanbases also gave the world the massive piles of bilious excremental garbage called Twilight, middle-aged men who play with ponies, and cancerous Talimancers.
Ultimately, creators of anything (unless they're doing it on commission, of course) listen only for the sounds of our wallets opening/closing, and our opinions mean precisely nothing to the so-called "creative process".
The fans will not determine anything about ME4 except how much or little revenue it generates for EA.
It is nice, however, that some optimism is left in BSN, misplaced though it is.